SACRAMENTO — State officials Friday ignored warnings that San Quentin state prison’s new death row will cost more $300,000 per cell and voted unanimously to approve the project’s preliminary construction plans.

It was the last public vote necessary before construction can begin.

“This is a $1 billion boondoggle, and the governor is still asleep,” Assemblyman Joe Nation, D-San Rafael, said after the packed meeting of the state Public Works Board. “This is a huge disappointment.”

The public works board’s 3-0 vote came just hours before Sacramento Superior Court Judge Lloyd Connelly denied Marin County’s request for a temporary restraining order to block the state Department of Corrections and Rehabilitation from taking further action on the project.

“I don’t see that there will be any irreparable harm occurring in the next 15 days,” Connelly said. “The project isn’t due to break ground until June 2006.”

Connelly’s ruling was in response to a lawsuit filed Wednesday by the Marin County Board of Supervisors. The suit claims the state Department of Finance violated state code when it approved a revised scope for the $233 million, 768-cell maximum-security facility.

Connelly set a Nov. 21 hearing date on the county’s lawsuit.

The death row, to be built on the bayfront near Larkspur Landing, was approved by the state Legislature in 2003 for 1,024 cells at a cost of $220 million but in August was shrunk to 768 cells after projected costs rose to $265 million.

At $233 million, the new proposal is a 6 percent increase in cost from the original $220 million. But the county argues that with the reduced scope, it amounts to an effective 30 to 35 percent increase in the price tag.

“Obviously this can’t be a good decision,” Marin County Supervisor Steve Kinsey told the Public Works Board. “This is the most expensive land in California — bayfront land in a vibrant urban setting — and the most difficult place to staff a prison and the highest cost of construction.”

But former San Quentin Warden Jeanne Woodford said the need for more secure death row housing was critical, noting two death row inmates almost escaped because of faulty security.

“We’ve run out of room, and the public safety risks in our current facility are very clear,” said Woodford, now state Corrections Department undersecretary. “We need a modern facility.”